There has been available an e-commerce system in which, through an online shopping site that constructs a virtual mall with a plurality of virtual shops on the Internet, goods can be purchased at a shop corresponding to each of the virtual shops. In this e-commerce system, when a user makes a credit card transaction upon the purchase of goods at a shop, a server of the virtual mall sends a credit card number of the user to a shop terminal so that the shop terminal sends a credit inquiry or a request for the settlement of the sales based on the credit card number of the user to a credit card company.
In a case where actual credit card numbers of the users are forwarded to the shop, the shop needs to bear enormous human and economic costs incurred in the management of the credit card numbers of the users. As such, as described in Patent Literature 1 below, there has been proposed a system in which an intermediary settlement system issues a virtual card number to a user in advance, and performs settlement process based on the virtual card number inputted at the time of the order.